Lockwood published the first novel, Travels and adventures of Little Baron Trump and his wonderful dog Bulger, in 1889, and its sequel, Baron Trump's Marvellous Underground Journey, in 1893. The novels recount the adventures of the German boy Wilhelm Heinrich Sebastian Von Troomp, who goes by "Baron Trump", as he discovers weird underground civilizations, offends the natives, flees from his entanglements with local women, and repeats this pattern until arriving back home at Castle Trump.